KR20040088504A - Fluorescent magnetic flaw detector and fluorescent magnetic flaw detecting method - Google Patents

Abstract

In order to obtain a clear bright fluorescent magnetic powder image, and to provide a fluorescent magnetic powder flaw detector which is inexpensive and inexpensive or excellent in water retention by eliminating complicated mechanisms, the fluorescent light magnetic flaw detector has a light source 26 ) Is a strobe light, and the image pickup device 30 has a band pass filter 32 which transmits only the spectral band of fluorescence on its front face, and opens the shutter only for the light emission time of the strobe light, and a video signal multiplication function. It is set as the CCD camera which added. As a result, a clear fluorescence magnetic particle shape can be obtained, and the relative speed of the inspected material and the flaw detector can be increased.

Description

Fluorescent magnetic particle flaw detector and fluorescent magnetic particle flaw detector {FLUORESCENT MAGNETIC FLAW DETECTOR AND FLUORESCENT MAGNETIC FLAW DETECTING METHOD}

Hot-rolled steel products such as hot rolled steel strips, thick plates, steel pipes, and crude steels have scales or oil dirt attached to their surfaces, or roughness is rough compared to cold-rolled products, which makes it difficult to automate surface defect inspection. Therefore, conventionally, only the inspector visually confirmed or when the detection precision was needed, and resorted to the visual inspection by the magnetic particle flaw detection method.

In fluorescence magnetic particle inspection in which fluorescence magnetic particles are applied in the magnetic particle inspection, when ultraviolet rays are irradiated to the fluorescence magnetic particles integrated in the defect portion, there is an advantage that the disturbing factors such as the scale of the surface are suppressed and only the defect portion is present. In recent years, there have been attempts to automate by taking advantage of this advantage by imaging and signal processing a fluorescent magnetic particle shape with a TV camera. However, since the fluorescence obtained by irradiating ultraviolet rays is weak compared to normal light illumination, when the relative speed of the inspected material and the TV camera increases, defects extending in the direction perpendicular to the traveling direction and blurring the image with the image flow are significantly signaled. There was a problem that the level was lowered.

In order to cope with these problems, the conventional apparatus has provided a mirror oscillation mechanism for canceling the relative movement speed with the inspection object or an imitation mechanism of the conveying device for suppressing the relative movement of the inspection object and the imaging device. One of the conventional automatic flaw detection apparatuses captures with a TV camera approximately synchronizing with the movement of an imaging part via a scanning mirror while driving a test | inspection material to a longitudinal direction, and improves the defect detection precision (for example, Japanese Patent Laid-Open No. 4). -65660). In addition, in another automatic flaw detector, the inspection material is fixedly installed, a scan mirror and a TV camera are installed on a carriage traveling in the longitudinal direction, and the image is captured by the TV camera in synchronism with the movement of the image pickup site via the scan mirror. The defect detection accuracy is improved (for example, see Japanese Patent Laid-Open No. 5-273150).

There are several problems with the prior art. As described in JP-A-5-273150, it is necessary to generate a distance signal by a pulse generator or the like attached to the touch roll in order to achieve accurate synchronization. However, an error may arise by slipping between an inspection material and a touch roll. In addition, if the object to be shaken or bent when conveying the material to be inspected, an image flow in a direction that cannot be followed by the vibration mirror occurs. Regarding the apparatus disclosed in Japanese Unexamined Patent Publication No. Hei 4-65660, problems related to relative fluctuation and bending of the inspected material occur. In addition, the higher the relative speed, the larger the tilt angle of the mirror, and consequently becomes the same as viewed obliquely, resulting in an optically distorted image. In addition, such mechanical mechanisms have problems such as complexity, expensiveness, and poor water retention when attempting to improve accuracy.

In order to solve these problems, it is only necessary to be able to take a still image instantaneously, and this is possible by stroboscopic illumination in normal TV shooting or the like. However, in the spectrum of a normal flash bulb, only a few ultraviolet components are included, and the magnetic particles collected at a defective part by magnetic particle inspection are very small. Therefore, only a weak fluorescent image is usually obtained, and there is a problem that sufficient sensitivity cannot be obtained with a normal TV camera and ultraviolet strobe lighting.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent magnetic particle flaw detector and a fluorescent magnetic particle flaw detector suitable for use in automatic surface flaw flaw detectors, particularly hot rolled products and welded surfaces thereof, for steelmaking products.

Fig. 1 shows one embodiment of the present invention, and is a schematic side view of a fluorescent magnetic particle flaw detector.

Fig. 2 shows another embodiment of the present invention, and is a schematic side view of a fluorescent magnetic particle flaw detector.

FIG. 3 is a plan view of the fluorescent magnetic particle flaw detector shown in FIG.

4 is a perspective view of an iron core of a magnetization device of a fluorescent magnetic particle flaw detector according to the present invention.

FIG. 5 is a circuit diagram of a power supply and a magnetizing coil of the magnetization device shown in FIG.

6 is a graph of the magnetization current supplied to the electromagnet of the fluorescent magnetic particle inspection device according to the present invention.

Fig. 7 shows still another embodiment of the present invention and is a schematic side view of a fluorescent magnetic particle flaw detector.

FIG. 8 is a plan view of the fluorescent magnetic particle flaw detector shown in FIG. 7.

9 is a circuit diagram of a power supply and a magnetizing coil of the fluorescent magnetic particle flaw detector according to the present invention.

FIG. 10 is a cross-sectional view of another embodiment of the light source shown in FIG. 9 in part.

Fig. 1L is a diagram showing an embodiment in which a light source and an imaging device are arranged outside the magnetizer in the fluorescent magnetic particle flaw detector according to the present invention.

Fig. 12 is an embodiment based on claim 4 of the present invention, showing an example of imaging from the outside with a magnetizer of an X-type or concealed yoke.

FIG. 13 is an embodiment based on claim 5 of the present invention, which shows an example of measuring an imaging position with a movement distance meter and recording a defect position. FIG.

Disclosure of Invention The present invention solves the problems described above and provides a bright fluorescent fluorescent powder image, and provides a fluorescent magnetic powder flaw detector with low cost and excellent water retention by eliminating complicated mechanisms such as a mirror swing mechanism and an imitation mechanism. I am doing it. The gist of the present invention is as follows.

(1) A magnetization apparatus for magnetizing the surface layer portion of a welded portion of a steel or steel member to be inspected, a magnetic liquid dispersion nozzle for dispersing magnetic liquid onto the surface of the inspected material, an ultraviolet irradiation device for irradiating the inspected surface, and an inspected surface. In the fluorescent magnetic particle inspection device comprising an image pickup device for imaging and an image processing device for processing the screen to pick up and determine the presence or absence of scratches,

The imaging device has a band pass filter which transmits only the spectral band of fluorescence on its front face, and has a function of opening the shutter only for the light emission time of the strobe light and adding a video signal multiplication function. Fluorescent magnetic particle flaw detection apparatus which made it possible to speed up the relative speed | rate.

(2) The magnetizer is provided with four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface and the magnetic poles form a square vertex, and at the right side of the square, The magnetic poles are arranged so as to form a plurality of squares by increasing the poles, and the pairs of magnetic poles arranged at the diagonal points of the newly formed squares are paired substantially to form a pair of electromagnets, and the magnets alternately in phase with each electromagnet at the same frequency. It is a magnetization apparatus which produces | generates a some rotating magnetic field in a to-be-tested surface through an electric current, The fluorescent magnetic particle flaw detector of (1) description characterized by the above-mentioned.

(3) The magnetizer is provided with four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface and the magnetic poles form a square vertex, and at the same time, the magnetization device is spaced at right angles to one side of the square. 4 poles are arranged by 4 poles to form a plurality of squares, and a joint member for shorting the poles is installed every 4 poles to maintain the symmetry of each of 4 poles. The magnetic field spectrometer according to (1), characterized in that the magnetization device generates a plurality of rotating magnetic fields on an inspected surface by passing a magnetization alternating current having a phase shifted at the same frequency through a pair of magnetizing coils.

(4) One or two or more pairs of quadrupole poles in which the magnetizer is arranged with two poles, ie, a pair of electromagnets, axially symmetrical around an axis perpendicular to the inspection surface and with magnetic poles forming a vertex of a rectangle or a square. Magnetization alternating current consisting of a pair of magnetic poles of each pair of electromagnets short-circuited with a connecting member, and a pair of magnetizing coils wound around a pair of poles of each pair of magnets It is a magnetization apparatus which produces | generates one or several rotating magnetic field in the to-be-tested surface through, The fluorescent magnetic particle flaw detector of (1) description characterized by the above-mentioned.

(5) Surface-surface flaw of the to-be-inspected material detected using the moving distance information measured with the distance measuring device provided with the distance measuring device which measures the moving distance of each point on the to-be-tested surface which moves relatively with respect to the imaging position of the said imaging device. The fluorescent magnetic particle flaw detector according to any one of (1) to (4), which is characterized in that it is mapped.

(6) magnetizing the surface layer portion of the welded portion of the steel or steel member to be inspected; self-dispersion dispersing to disperse the magnetic liquid onto the surface of the inspected material; irradiating ultraviolet to the inspected surface; and imaging the inspected surface; In the fluorescence magnetic particle inspection method comprising the image processing step of processing the captured screen to determine the presence or absence of scratches,

In the imaging step, an inspection material and flaw detection are performed by a series of steps using a band pass filter that transmits only the spectral band of fluorescence, and using a CCD camera that only opens the shutter for the light emission time of the strobe light and adds an image signal multiplication function. Fluorescent magnetic particle flaw detection method which made it possible to speed up the relative speed of an apparatus.

(7) The magnetizing step includes the installation of four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface, and the magnetic poles form a square vertex, and at right angles to one side of the square. The two poles are arranged so that the magnetic poles form a plurality of squares, and the pairs of magnetic poles arranged at the diagonal points of the newly formed square are paired with each other to substantially form a pair of electromagnets at the same frequency in each electromagnet. It is a magnetization method which produces | generates a some rotating magnetic field in the to-be-tested surface through the alternating magnetization alternating current, The fluorescence magnetic particle flaw detection method of (6) description.

(8) The magnetizing step includes the installation of four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface and the magnetic poles form a square vertex, and at the same time in a direction perpendicular to one side of the square. 4 poles are arranged at intervals of 4 poles to form a plurality of squares, and a joint member for shorting the poles is installed every 4 poles to maintain symmetry of each 4 poles and to make a pair of diagonal magnetization coils. The magnetic flux detection method according to (6), which is a magnetization method of generating a plurality of rotating magnetic fields on an inspected surface by passing a magnetization alternating current having a phase shifted to two pairs of magnetization coils at the same frequency.

(9) The magnetizing step is a pair of two poles, that is, a pair of four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface, and the magnetic poles form a rectangular or square vertex. The magnetization alternating current which comprised the above and short-circuited the diagonal pole or four poles of each pair of electromagnets with a joint member, and shifted the phase to the two pairs of magnetization coils wound by the pair of poles of each pole at the same frequency. (6) The fluorescence magnetic particle flaw detection method according to (6), characterized in that it is a magnetization method for generating one or a plurality of rotating magnetic fields on the inspected surface by passing through.

(10) measuring the movement distance of each point on the inspection surface moving relatively to the imaging position of the imaging step, and mapping the surface flaws of the inspection object detected using the movement distance information measured by the distance measuring device; The fluorescent magnetic particle flaw detection method in any one of (6)-(9) characterized by the above-mentioned.

As described above, the fluorescent magnetic particle flaw detector according to the present invention includes a CCD camera with the function of opening the shutter only for the light emission time of strobe light and adding a video signal multiplication function. This makes it possible to obtain a sharp and sharp image with no shaking, similarly to still image shooting, even when moving or swinging in any direction. In addition, even a weak fluorescent image by ultraviolet strobe can be photographed with sufficient sensitivity, and a clear bright fluorescent magnetic particle image can be obtained. For this reason, defect detection precision improves significantly.

In the present invention, the magnetizing device is provided with four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface and so that the magnetic poles form a square vertex, and at the right angle to one side of the square. Two poles in the direction to form a plurality of squares, and a pair of magnetic poles arranged at diagonal points of the newly formed squares, respectively, to form a pair of electromagnets, and to shift phases at the same frequency to each electromagnet. Since a plurality of rotating magnetic fields are generated on the inspected surface through the alternating magnetization current, the inspected material is magnetized while passing through the plurality of electromagnets to be aligned one by one, so that the magnetization time is long and vivid fluorescence even when the inspected material moves at high speed. Magnetic powder shape is formed.

In addition, in the present invention, the magnetizing device is provided with four poles in which a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspected surface and the magnetic poles form a square vertex, and at the same time in a square direction. 4 poles are arranged at intervals of 4 poles so as to form a plurality of squares. A joint member for shorting the poles is provided every 4 poles to maintain the symmetry of each of 4 poles. In this case, the pair of magnetizing coils is configured to generate a plurality of rotating magnetic fields on the surface to be inspected by passing through a magnetization alternating current having a phase shifted at the same frequency. Therefore, the magnetization time is long, and a clear fluorescent magnetic powder shape is formed even when the inspected material moves at high speed. Moreover, all the rotating magnetic fields can be equalized without adjusting the coil winding number, power supply voltage, etc. for every electromagnet. By equalizing the rotating magnetic field, defect detection performance is increased.

In addition, in the present invention, the magnetization device includes a pair of four-pole l electromagnets in which two poles, i.e., a pair of electromagnets are arranged axially symmetrically around an axis perpendicular to the inspection surface, and the magnetic poles form a rectangular or square vertex. It consists of a pair or two or more pairs, shorts the diagonal poles or four poles of the electromagnets of each pair with a joint member, and shifts the phase at the same frequency to two pairs of magnetization coils wound around the pair of poles of each pole. The magnetization time may be extended by generating one or a plurality of rotating magnetic fields on the inspected surface through one magnetization alternating current.

In addition, in this invention, when it is necessary to confirm the position of each flaw detected by the fluorescent magnetic particle flaw detector, the movement distance of each point on the test surface which moves relatively with respect to the imaging position of an imaging device is carried out on the test surface. A distance measuring device measuring based on a certain point can be assembled into a fluorescent magnetic particle inspection device, and surface flaws of the inspected material detected using the moving distance information measured by the distance measuring device can be mapped to facilitate the subsequent processing of the scratches. .

EMBODIMENT OF THE INVENTION Below, this invention is demonstrated, referring drawings.

Fig. 1 shows one embodiment of the present invention and is a schematic configuration diagram of a fluorescent magnetic particle flaw detector. The fluorescent magnetic powder flaw detector is composed of a magnetization device 10, a magnetic liquid dispersion device 20, an ultraviolet irradiation device 25, an imaging device 30, and an image processing device 35.

The magnetization apparatus 10 consists of the electromagnet 11 by which the magnetization coil 18 was wound by the leg part 14 of the c-shaped iron core 12. The magnetization coil 18 is supplied with direct current from a direct current power source (not shown). In addition, the magnetizing coil 18 may be wound around the joint member 16 which connects the upper part of the leg part 14. As shown in FIG.

The magnetic powder dispersion | distribution apparatus 20 is equipped with the magnetic liquid injection nozzle 21 and the washing | cleaning water supply nozzle 22. As shown in FIG. A magnetic powder tank is connected to the magnetic powder injection nozzle 21, and a water supply tank is connected to the washing water supply nozzle 22, respectively, and the magnetic powder or the washing water is supplied by a pump (all are not shown in the figure). Instead of the washing water supply nozzle 21, an air purge nozzle that blows out air may be used.

The ultraviolet irradiation device 25 has an ultraviolet strobe light source 26. The ultraviolet strobe light source 26 is, for example, a combination of a xenon flash lamp and a U340 filter. In the bulb of the xenon flash lamp, a material that transmits even hard ultraviolet rays is used. The light emission time of the xenon flash lamp is about 10 mW. The U340 filter transmits ultraviolet light of about 310 to 390 nm, which is relatively safe for humans among stroboscopic lights that emit and emit light in a broad spectrum from rigid ultraviolet light to infrared light.

The imaging device 30 is a combination of an imaging unit 31 and a band pass filter 32 made of a CCD camera having a function of opening the shutter only for the light emission time of strobe light and adding a video signal multiplication function. Here, the MCP type CCD camera made by Hamamatsu TV Co., Ltd. is used as a CCD camera. In this CCD camera, the optical image incident on the image multiplier is converted into photoelectrons on the photoelectric surface. Optoelectronics are amplified thousands of times in microchannel plates and become optical images again on the fluorescent surface. The shutter (gate) operation is controlled by the potential between the photoelectric surface-micro channel plate. The gate operation is on (shutter-open) when the micro channel plate potential is higher than the photoelectric surface potential, and off when it is low.

Band pass filter 32 transmits only the spectral components of fluorescence. Irradiation light from the ultraviolet irradiation device 25 includes ultraviolet rays for fluorescence excitation and infrared rays which are more rarely leaked than the U340 filter. Since the imaging unit 30 has wavelength sensitivity from the ultraviolet to the infrared region, the ultraviolet and infrared rays are also input. The band pass filter 32 blocks these ultraviolet rays and infrared rays, and increases the SN ratio of the image.

The image processing apparatus 35 performs density correction, smoothing, binarization processing, etc. on the image signal from the imaging device 30, and determines the presence or absence of a flaw. The discrimination criteria are created on the basis of inspection data obtained in actual industry, and are stored in the image processing apparatus in tabular form.

In the fluorescent magnetic particle flaw detector configured as described above, the inspected material 1 is a drum-shaped welding structure in which a thick plate is bent and moved in the direction of an arrow. The inspected portion is a welded portion extending in the circumferential direction. The magnetization apparatus 10 magnetizes a direct current so that a magnetic flux may cross a welding part. The fluorescent magnetic powder is dispersed from the magnetic liquid jet nozzle 21 in the magnetized welding part. If there is a defect in the surface layer portion of the inspected material 1, leakage magnetic flux is generated in the defect portion. Fluorescent magnetic particles in the magnetic liquid are attracted to the leaked magnetic flux, accumulate in the defect portion, and form a fluorescent magnetic powder shape. The washing water scattered from the washing water supply nozzle 22 flows backward along the surface of the thick plate 1 to wash away the excess magnetic liquid. In general, since the leakage magnetic flux of the defective part is stronger than the leakage magnetic flux caused by the unevenness of the defective part, only the unnecessary magnetic part of the defective part is washed when cleaning at an appropriate flow rate. As a result, the SN ratio of the image picked up by the imaging device 30 becomes high.

The ultraviolet strobe light source 26 emits fluorescent light magnetically integrated into the defect portion by irradiating an ultraviolet pulse from above. The light emission time of the ultraviolet strobe light source 26 is about 10 mu sec, as described above. The shutter of the CCD camera is adjusted to open only this light emission time. Normally, the frame rate of a CCD camera is 30 Hz, 33 msec. Therefore, the influence of the image flow and the illuminance of the surrounding environment is about 1/3300. At such a short light emission time, the inspected material moving almost appears to be in a stationary state, and thus, it is possible to image a clear fluorescent magnetic particle without any phase flow. Thereby, even the micro crack which was not able to detect conventionally only in the state which stopped the to-be-tested material can be detected, and the defect detection precision can be improved significantly.

2 to 5 show another embodiment of the present invention. Fig. 2 is a schematic side view of the fluorescent magnetic particle flaw detector, Fig. 3 is a plan view, Fig. 4 is a perspective view of an iron core of the magnetizing device, and Fig. 5 is a circuit diagram of a power supply and a magnetizing coil of the magnetizing device. In this embodiment, the same reference numerals are given to those similar to the apparatus and member shown in FIG. 1, and the detailed description thereof is omitted.

In magnetic particle flaw detection, two-way magnetization in the advancing direction of an inspection material and a direction orthogonal to this may be required. In such a case, it is necessary to magnetize the inspected material to a rotating magnetic field. In the fluorescent magnetic particle flaw detector according to this embodiment, the magnetization device generates a rotating magnetic field.

The fluorescent magnetic powder flaw detector comprises a magnetization device 40, a magnetic liquid dispersion device 20, an ultraviolet irradiation device 25, an imaging device 30, and an image processing device 35. Since the magnetic liquid dispersion device 20, the ultraviolet irradiation device 25, the imaging device 30, and the image processing device 35 are the same as those shown in FIG. 1, the description thereof is omitted.

The magnetizer 40 is composed of three sets of magnetizers 41, 42, and 43 provided with electromagnets and a power source for supplying magnetization current to these magnetizers. The iron core 60 of the electromagnet has four c-shaped iron cores 61 to 64 arranged in a line at equal intervals. Both end portions of the first c-shaped iron core 61 and both ends of the second c-shaped iron core 62 are connected to the joint member 70 to form a first quadrangle iron core 57. In addition, both end portions of the second c-shaped iron core 62 and both end portions of the third c-shaped iron core 63 are connected to the joint member 70 to form a second square iron core 58. Similarly, the third square iron core 59 is formed. The distance between the first c-shaped iron core 61 and the second c-shaped iron core 62 in the first square iron core 57 is a leg portion 61A, B or 62A ', B' of the first c-shaped iron core 61. It is equal to the interval of. Thus, the four legs 61A, B, 62A ', B' are located at the vertices of the square. Similarly, in the second square iron core 58 and the third square iron core 59, four leg portions are located at the vertices of the square.

Magnetization coils 75A, B to 78A ', and B' are wound around each of the leg portions 61A, B to 64A ', and B'. Among these magnetizing coils 75A, B to 78A ', and B', one electromagnet is composed of the magnetizing coils facing each other in the diagonal direction and the c-shaped iron core and the joint member 70. For example, in the first magnetizer 41, one electromagnet 51 is composed of the c-shaped iron cores 61 and 62, the coupling members 70, and the magnetization coils 75A and 76A ', and the magnetization coil 75B. 76B ', another electromagnet 54 is constructed. Similarly, the electromagnets 52 and 55 are configured in the second magnetizer 42 and the electromagnets 53 and 56 are configured in the third magnetizer 43, respectively.

The magnetization device 40 includes six sets of electromagnets including three sets of electromagnets 51, 52, and 53 and three sets of electromagnets 54, 55, and 56. That is, four poles are provided in which a pair of electromagnets are arranged axially symmetrically around the axis perpendicular to the inspected surface and the magnetic poles form a square vertex. The magnetic poles are formed by extending two poles in a right direction on one side of the square to form three squares, and a pair of magnetic poles arranged at diagonal points of the newly formed squares are paired substantially to form a pair of electromagnets.

5 shows a circuit of magnetizing coils 75A to 78B 'and a power supply 80. As shown in FIG. The AC transmitter 81 is connected to the magnetizing coils 75A and 76A 'and the magnetizing coils 77A and 78A' facing each other in the square direction via the power amplifier 83. The alternating current generator 81 is connected to the magnetizing coils 75B and 76B 'and the magnetizing coils 77B and 78B' facing in the other diagonal direction via a 90 ° phase 85 and a power amplifier 86. The power amplifiers 83 and 86 supply the alternating magnetization current of a predetermined frequency to each magnetizing coil 75A-78B 'by the signal from the AC transmitter 81. As shown in FIG. The magnetizing coils 75B, 76B ', 77B, and 78B' are supplied with an alternating magnetizing current that is out of phase by 90 ° with respect to the magnetizing coils 75A, 76A ', 77A, and 78A'. FIG. 6 shows a case where magnetization alternating currents having the same frequency and a phase difference of 90 ° are supplied to the electromagnets 54, 55, and 56 with respect to the electromagnets 51, 52, and 53. As shown in FIG. In addition, the phase difference may be 120 ° using a three-phase AC current power supply.

In this embodiment, the number of magnetizers is three, but the number of magnetizers is changed depending on the flaw detection conditions and the line speed (test moving speed). For example, it is recommended that the magnetic particle spreading time be 5 seconds or more. Therefore, when the magnetic pole interval is lp [cm] and the line (inspection material) speed is V [cm / sec], the passage time Tf of one magnetizer becomes Tf = lp / V.

If n = 5 sec / Tf sec,

Integer greater than n + 2 magnetizer (magnetizer of purge part + magnetizer of imaging part)

It is preferable to make the number of magnetizers.

The magnetic liquid jet nozzle 21 and the washing water supply nozzle 22 are disposed in the second magnetizer 42. The ultraviolet irradiation device 25 and the imaging device 30 are disposed directly above the third magnetizer 43.

In the fluorescence magnetic particle inspection device configured as described above, the thick plate 1 is sent in the direction of the arrow in a state inclined with respect to the horizontal plane in order to wash away the excess fluorescence magnetic powder with washing water. The magnetization device 40 is arranged such that the U-shaped iron cores 61 to 64 span the welding line 5. Since the magnetization alternating currents having the same frequency and phase difference of 90 ° are supplied to the electromagnets 54 to 56 with respect to the electromagnets 51 to 53, a rotating magnetic field R is generated on the inspected surface for each magnetizer. The rotating magnetic field R is of equal magnitude in the direction of the weld line and at right angles thereto. The magnetic field rotational direction of the second magnetizer 42 is opposite to the magnetic field rotational direction of the first magnetizer 41 and the third magnetizer 43.

Since the rotating magnetic field R is an alternating magnetic field, it is demagnetized when the magnetized portion of the rear plate 1 is spaced apart from the magnetic poles. However, in the magnetization apparatus 40 of this embodiment, since it is magnetized for every magnetizer, the magnetic powder attached to the defect part by the 2nd magnetizer 42 is hold | maintained also in the 3rd magnetizer 43. As shown in FIG.

In general, a certain amount of time is required before the magnetic powder in the dispersed magnetic liquid moves to the defect portion and accumulates to form a fluorescent magnetic powder. Therefore, when magnetically flamming a thick plate moving at high speed, the length of the magnetizing device must be made long according to the moving speed of the thick plate. On the other hand, in order to generate the rotating magnetic field as described above, the magnetic pole must be placed at the square vertex. The narrower the magnetic pole spacing of the magnetization device, the higher the magnetic flux density is generated between the magnetic poles between the magnetic poles, so that the interval between adjacent U-shaped iron cores is narrowed and sufficient time is not obtained to form the fluorescent magnetic particles. In this embodiment, three magnetizers 41, 42, and 43 are magnetized, respectively, so that the magnetization time is long, and a clear fluorescent magnetic powder shape is formed even when the thick plate 1 moves at high speed. The number of magnetizers can be increased or decreased by the feed rate or the speed of flaw detection.

7 to 9 show yet another embodiment of the present invention. Fig. 7 is a schematic side view of the fluorescent magnetic particle flaw detector, Fig. 8 is a plan view of the apparatus, and Fig. 9 is a circuit diagram of the power supply and magnetization coil of the magnetization apparatus.

The fluorescent magnetic powder flaw detector comprises a magnetization device 90, a magnetic liquid dispersion device 20, an ultraviolet irradiation device 25, an imaging device 30, and an image processing device 35. Since the magnetic liquid dispersion device 20, the ultraviolet irradiation device 25, the imaging device 30, and the image processing device 35 are the same as those shown in FIG. 1, the description thereof is omitted.

The magnetization device 90 is composed of three sets of magnetizers 91, 92, and 93 provided with electromagnets and a power supply for supplying magnetization current to these magnetizers. The iron core of the first magnetizer 91 is a first square iron core 107 formed by connecting both end portions of the first c-shaped iron core 110 and both ends of the second c-shaped iron core 111 to the joint member 112, respectively. ) In addition, the iron core of the second magnetizer 92 is a second square iron core formed by connecting both ends of the third c-shaped iron core 113 and both ends of the fourth c-shaped iron core 114 with the joint member 115, respectively ( 108). Similarly, the third square iron core 109 of the third magnetizer 93 is formed. The distance between the first c-shaped iron core 110 and the second c-shaped iron core 111 in the first magnetizer 91 is a leg portion 110A, B or 11 lA ', B' of the first c-shaped iron core 110. It is equal to the interval of. Thus, the four legs 110A, B, 11LA ', B' are located at the vertices of the square. Similarly in the second magnetizer 92 and the third magnetizer 93, the four legs are located at the vertices of the square.

The magnetizers 91, 92, 93 are arranged so that the interval between the magnetic poles of the magnetizers adjacent to each other in the plate direction is equal to the interval between the magnetic poles of each magnetizer. For example, the interval between the magnetic pole of the leg portion 11lB 'of the first magnetizer 91 and the magnetic pole of the leg portion 113A of the second magnetizer 92 is equal to the leg portion of the first magnetizer 91. 110A, 11lB '). The number of magnetizers is determined in accordance with the flaw detection conditions and the line speed (speed of inspected material moving) as in the case of the apparatus shown in FIG.

Magnetization coils 121A, B to 126A ', and B' are wound around each of the leg portions 110A, B to 117A ', and B'. Among these magnetizing coils 121A, B to 126A ', and B', a magnet is formed with the magnets facing each other in the diagonal direction, the c-shaped iron core, and the joint member constitute one electromagnet. For example, one electromagnet 101 is constituted by the U-shaped iron cores 110 and 111, the iron core 112, and the magnetization coils 121A and 122A '.

The magnetization device 90 is provided with six sets of electromagnets including three sets of electromagnets 101, 102 and 103 and three sets of electromagnets 104, 105 and 106. That is, four poles are provided in which a pair of electromagnets are arranged symmetrically about an axis perpendicular to the inspection surface and with magnetic poles forming a square vertex. In addition, the poles are stretched by four poles at right angles to one side of the square to form three squares, and the pairs of magnetic poles disposed on the diagonal points of the newly formed square are paired substantially to form a pair of electromagnets. have.

9 shows the circuits of the magnetizing coils 121A to 126B 'and the power supply 130. The AC transmitter 131 passes through the power amplifier 133 through the magnetizing coils 121A and 122A ', the magnetizing coils 123A and 124A', and the magnetizing coils 125A and 126A 'facing each other in the diagonal direction. Connected. Alternating magnetization coils 121B, 12B ', magnetizing coils 123B, 124B' and magnetizing coils 125B, 126B 'facing in the opposite diagonal direction through a 90 ° phaser 135 and a power amplifier 136 The transmitter 131 is connected. The power amplifiers 133 and 136 supply alternating magnetization currents of a predetermined frequency to the respective magnetizing coils 121A to 126B 'by signals from the AC transmitter 131. The magnetizing coils 121B, 122B ', 123B, 124B' and 125B, 126B 'are supplied with alternating magnetizing currents that are out of phase by 90 ° with respect to the magnetizing coils 121A, l22A' 123A, 124A 'and 125A, 126A'.

In the fluorescence magnetic powder flaw detector configured as described above, the magnetization device 90 is arranged so that the U-shaped iron cores 110, 111, 113, etc. span the welding line 5. Since the magnetization alternating current of 90 degrees of phase difference is supplied to the electromagnets 104-106 at the same frequency with respect to the electromagnets 101-l03, the rotating magnetic field R is produced in the inspected surface for every magnetizer. The rotating magnetic field R is of equal magnitude in the direction of the weld line and at right angles thereto. The magnetic field rotation direction of the 1st magnetizer 91, the 2nd magnetizer 92, and the 3rd magnetizer 93 becomes the same direction.

Since the rotating magnetic field R is an alternating magnetic field, it is demagnetized when the magnetized portion of the thick plate 1 is separated from the magnetic pole. However, in the magnetization apparatus 90 of this embodiment, since it is magnetized for every magnetizer, the magnetic powder adhering to the defect part in the 2nd magnetizer 92 is hold | maintained also in the 3rd magnetizer 93. As shown in FIG. In addition, in order to generate a plurality of rotating magnetic field strengths evenly, it is necessary to equalize the magnetic flux flowing in all A-A 'magnetic pole pairs and B-B' magnetic pole pairs. In this embodiment, if the number of turns of all magnetizing coils is the same, and voltage is applied in parallel as shown in Fig. 9, all rotating magnetic fields can be equalized without adjusting the number of coil turns, power supply voltage, etc. for each magnetizer. .

10 shows another embodiment of a light source. The light source 140 includes a pair of LED panels 142 in which dozens of LEDs 144 emitting in the ultraviolet region are arranged in a matrix form. The LED panel 142 is provided between the leg portion 116A (not shown) and the leg portion 117B 'of the third magnetizer 93 shown in FIG. 7 and the leg portion 116B (not shown in the figure). And the legs 117A ', and are disposed near the lower ends of these legs. The LED 144 receives a pulse current from a power supply (not shown), emits light, and irradiates the inspection surface. Since the strobe light source can be miniaturized in this LED light source 140, it can be arrange | positioned in the vicinity of an observation position. Therefore, the lighting efficiency is increased, and the power supply is also miniaturized.

Fig. 11 shows an embodiment in which the light source and the imaging device are outside the magnetizer. The magnetizer is an example using a joint member type (square yoke).

12 shows an embodiment of claim 4 and FIG. 13 shows an embodiment of claim 5, respectively. In Fig. 12, the magnetization of the X-type or concealed yoke is taken from the outside. Fig. 13 shows an example in which the defect position is recorded by measuring the imaging position with a movement distance meter.

Moreover, although the MCP type CCD camera which combined the image multiplier with a shutter function, and the CCD camera was used in embodiment mentioned above, what is necessary is just an ultra-high sensitivity camera which has a shutter function and a video signal multiplication function basically, for example, a hippo EB-type CCD cameras equipped with shutter functions developed by Matsus Photonics Co., Ltd. or impact-type CCD cameras made by Texas Instruments may be used. In addition, the LED light source shown in FIG. 10 is also applicable to the apparatus of FIG.

The fluorescent magnetic particle inspection device of the present invention has a CCD camera with the function of opening the shutter only for the light emission time of the stroboscopic light and a function of multiplying the video signal, so that there is no shaking as in still photography, even when moving or shaking in any direction. It is possible to obtain a clear bright fluorescent magnetic powder image. In addition, even a weak fluorescent image by ultraviolet strobe can be captured with sufficient sensitivity. For this reason, the defect detection accuracy is greatly improved, and the high precision of automatic inspection is attained. In the ultraviolet irradiation device and the imaging device, complicated mechanisms such as a mirror swing mechanism and an imitation mechanism are no longer needed, resulting in low cost and improved water retention. In addition, in the conventional fluorescent magnetic particle flaw detector, it was necessary to provide a dark room, but the necessity was eliminated in indoor working environment. In this regard, the facility and the operation are simplified by inspection of the assembly weld of the structure. Even in the outdoors, fluorescent magnetic particle inspection can be performed as much as a ceiling cover that protects against direct sunlight.

In the fluorescence magnetic particle inspection device configured to form a rotating magnetic field in a plurality of electromagnets in which four magnetic poles are arranged at square vertices, the magnetization time is long because the material to be inspected is sequentially magnetized while passing through a plurality of electromagnets to align. Even if the inspected material moves at high speed, a clear fluorescent magnetic powder shape is formed.

(Explanation of the sign)

1: thick plate, steel plate (inspection material)

5: welding line (inspection part)

10: magnetization device

11: electromagnet

12: U-shaped iron core

18: magnetization coil

20: liquid-liquid dispersion device

21: magnetic liquid jet nozzle

22: washing water supply nozzle

25: UV irradiation device

26: ultraviolet strobe light source

30: imaging device

31: imaging unit

32: band pass filter

35: image processing device

40: magnetizer

41 to 43: magnetizer

51 to 56: electromagnet

57 to 59: square iron core

70: joint member

75 to 78: magnetization coil

80: power

81: AC transmitter

83, 86: power amplifier

85: 90 ° phase machine

90: magnetization device

91, 92, 93: Magnetizer

101 to 106: electromagnet

107 to 109: square iron core

110, 111, 113, 114, 116, 117

112, 115, 118: joint member

121 to 126: magnetization coils

130: power

131: AC transmitter

133, 136: power amplifier

135: 90 ° phase

140: light source

142: LED Panel

144: LED

145: ICCD Camera

146: Strobe Lights

147: Magnetizer 1

148: magnetizer 2

149: position measuring instrument

150: square yoke

151: X type yoke

152: concealed yoke

Claims (10)

A magnetization apparatus for magnetizing the surface layer portion of a welded portion of a steel or steel member to be inspected, a magnetic liquid dispersion nozzle for dispersing magnetic powder onto the surface of the inspected material, an ultraviolet irradiation device for irradiating the inspected surface, and an image for imaging the inspected surface A fluorescence magnetic particle flaw detector comprising a device and an image processing device which processes the captured screen to determine the presence or absence of scratches, The imaging device has a band pass filter which transmits only the spectral band of fluorescence on its front face, and has a function of opening the shutter only for the light emission time of the strobe light and adding a video signal multiplication function. Fluorescent magnetic particle flaw detection apparatus which made it possible to speed up the relative speed | rate. The magnetization apparatus according to claim 1, wherein the magnetizing device installs a pair of electromagnets axially symmetrically around an axis perpendicular to the inspection surface, and has four poles arranged so that the magnetic poles form a square vertex, and is perpendicular to one side of the square. Two poles in the direction to form a plurality of squares, and a pair of magnetic poles arranged at diagonal points of the newly formed squares, respectively, to form a pair of electromagnets, and to shift phases at the same frequency to each electromagnet. And a magnetizing device for generating a plurality of rotating magnetic fields on an inspected surface through one magnetizing alternating current. The magnetization apparatus according to claim 1, wherein the magnetizing device installs a pair of electromagnets axially symmetrically around an axis perpendicular to the inspection surface, and has four poles arranged so that the magnetic poles form a square vertex, and is perpendicular to one side of the square. 4 poles are arranged in a plurality of squares at intervals of 4 poles at intervals in the direction, and a pair of magnetizing coils that maintains the symmetry of each of 4 poles is provided by installing a joint member for shorting the poles every 4 poles. And a magnetizing device for generating a plurality of rotating magnetic fields on an inspected surface by passing a magnetization alternating current having a phase shifted at the same frequency to two pairs of magnetizing coils. The pair of four-pole pairs according to claim 1, wherein the magnetizing device is arranged in two poles, that is, a pair of electromagnets axially symmetric around an axis perpendicular to the inspection surface, and the magnetic poles form a rectangular or square peak. Magnetization which consists of two or more pairs, the diagonal pole or four poles of the electromagnets of each pair are short-circuited by a joint member, and the two magnetization coils wound on the pair of poles of each pair were shifted in phase by the same frequency. And a magnetizing device for generating one or a plurality of rotating magnetic fields on an inspected surface through alternating currents. The moving distance measured in any one of Claims 1-4 provided with the distance measuring device which measures the moving distance of each point on the to-be-tested surface which moves relatively with respect to the imaging position of the said imaging device. A surface magnetic fluorescence flaw detector for mapping surface flaws of an inspection object detected by using information. Magnetizing the surface layer of the welded portion of the steel or steel member to be inspected, dispersing the magnetic liquid to disperse the magnetic liquid onto the surface of the inspected material, irradiating ultraviolet to the inspected surface, and imaging the inspected surface; In the fluorescence magnetic particle inspection method comprising the image processing step of processing the captured screen to determine the presence or absence of scratches, In the imaging step, an inspection material and flaw detection are performed by a series of steps using a band pass filter that transmits only the spectral band of fluorescence, and using a CCD camera that only opens the shutter for the light emission time of the strobe light and adds an image signal multiplication function. Fluorescent magnetic particle flaw detection method which made it possible to speed up the relative speed of an apparatus. 7. The square according to claim 6, wherein the magnetizing step includes installing a pair of electromagnets having a pair of electromagnets axially symmetrically arranged around the axis perpendicular to the inspection surface and the magnetic poles forming a square vertex. 2 poles in a direction perpendicular to each other to form a plurality of squares, and pairs of magnetic poles arranged at diagonal points of the newly formed squares to form a pair of electromagnets at substantially the same frequency in each electromagnet. And a magnetization method for generating a plurality of rotating magnetic fields on an inspected surface through a magnetization alternating current shifted in phase with a furnace. The method of claim 6, wherein the magnetizing step is performed at the same time as the step of installing the four poles in which the pair of electromagnets are arranged axially symmetrically around the axis perpendicular to the inspected surface and the magnetic poles form a square vertex. 4 poles are arranged to form a plurality of squares at intervals in the direction perpendicular to each other, and a joint member for shorting the poles every 4 poles is installed to maintain the symmetry of each of 4 poles and to form a diagonal magnetization coil. A magnetizing method for generating a plurality of rotating magnetic fields on an inspected surface by passing a pair of magnetizing alternating currents in which two pairs of magnetizing coils are shifted in phase by the same frequency. 7. The pair of four-pole pairs according to claim 6, wherein the magnetizing step comprises two poles, that is, a pair of four-pole pairs arranged with a pair of electromagnets axially symmetric around an axis perpendicular to the inspection surface, and the magnetic poles forming a rectangular or square vertex. Or it consists of two or more pairs, short-circuit poles or four poles of each pair of electromagnets were short-circuited by a joint member, and the phase was shifted at the same frequency to two pairs of magnetization coils wound by the pair of poles of each pole. And a magnetizing method for generating one or a plurality of rotating magnetic fields on an inspected surface by passing through a magnetization alternating current. The method according to any one of claims 6 to 9, further comprising the steps of measuring the movement distance of each point on the inspection surface moving relatively to the imaging position of the imaging step, and the movement distance information measured by the distance measuring device. And a step of mapping surface scratches of the test material detected using the fluorescence magnetic particle inspection method.